A little over thirty years ago, when he was in his mid-forties, my friend David Howorth lost all hearing in his left ear, a calamity known as single-sided deafness. "It happened literally overnight," he said. "My doctor told me, 'We really don't understand why.' " At the time, he was working as a litigator in the Portland, Oregon, office of a large law firm. His hearing loss had no impact on his job--"In a courtroom, you can get along fine with one ear"--but other parts of his life were upended. The brain pinpoints sound sources in part by analyzing minute differences between left-ear and right-ear arrival times, the same process that helps bats and owls find prey they can't see.

After a long run, Google is sunsetting two of its signature Nest products and consequently withdrawing as a manufacturer in two key smart home categories. Google has just announced that it's discontinuing the 10-year-old Nest Protect and the 7-year-old Nest x Yale lock. Both of those products will continue to work, and--for now--they remain on sale at the Google Store, complete with discounts until supplies run out. But while Google itself is exiting the smoke alarm and smart lock business, it isn't leaving Google Home users in the lurch. Instead, it's teeing up third-party replacements for the Nest Protect and Nest X Yale lock, with both new products coming from familiar brands.

Google just relaunched its Nest Aware home security plans, complete with a simplified pricing structure and a host of new features. Chief among them: the ability for Google smart displays and speakers to alert you if they hear something suspicious. Users who pony up $6 a month ($60 if paid annually) for the standard Nest Aware plan will be able to set their Google Home and Nest devices to detect the sound of breaking glass and smoke alarms. The subscription covers all the Nest devices in your home and includes 30 days of cloud storage for event recordings made by Nest security cameras ("events" are recordings triggered by motion or sound). A $12-per-month/$120-per-year plan gives you 60 days of event storage in the cloud, plus 10 days of 24/7 video recording.

Amazon Alexa will soon notice if you talk to it sotto voce--and whisper its response back to you. The new feature, announced by Amazon today alongside new devices including a microwave and a wall clock at an event in Seattle, is one of several upgrades that will expand the virtual assistant's ability to listen to and understand the world around it. Alexa will able to confer with you in whispers before the end of the year, making Amazon's voice operated assistant less awkward to use when someone is, say, sleeping nearby. Amazon will also make its assistant capable of listening out for trouble such as breaking glass or a smoke alarm when you're away from home, a feature called Alexa Guard. Meanwhile, inside Amazon's labs, the company is experimenting with giving Alexa a rudimentary form of emotional awareness, enabling it to listen for the sound of frustration in a person's voice.

Eighteen months ago, Marwan Fawaz became CEO of Nest. He spoke exclusively to The Independent. The company's latest products, in a shimmery white finish that almost matches the walls, are on the table. Nest is part of the Alphabet group – whose offices these are – which also includes Google. Fawaz had previously worked for another company in the group, Motorola Home.

In a sound-proofed hangar on an RAF airbase just north of Cambridge, UK, Chris Mitchell and his colleagues are busy using sledgehammers to teach their computers a lesson. The team has gathered thousands of window panes and doors, all of different shapes and sizes, which they then smash, one by one, recording the distinctive shattering sound of each type of glass. Sometimes they swing sledgehammers or garden spades, sometimes they throw bricks. "We completely underestimated the mess it would make," says Mitchell. "And how tiring it would be."

Netatmo is known for connected home products like the Presence AI-assisted security camera that can tell crooks from coyotes, but for CES, it's expanding into a new niche: built-in products. On top of a new smoke alarm and siren, the company has teamed up with French companies Velux and Legrand on AI-equipped in-wall smart switches, power outlets, skylights and blinds. On the consumer side, Netatmo launched the Smart Smoke Alarm (above) as an addition to its home security and monitoring lineup. Much like the Nest Protect, it sounds an 85 decibel alarm when it detects smoke, but also sends a real-time alert to your smartphone. That's accompanied by a message like "smoke detected in the kitchen," telling you where, exactly, the problem is.

Amazon's voice assistant Alexa has become a hugely popular and growing business. In fact, David Limp, an Amazon senior vice president who oversees Alexa and all of its Amazon devices, says that Alexa is rapidly adding "skills," with more than 1,000 people working on it. On Tuesday, at Fortune's Brainstorm Tech conference, Limp spoke to Fortune's Adam Lashinsky about the inspiration for Alexa (hint: Think Star Trek) and the origin of the name to where the business is heading. Here is the lightly-edited transcript. Dave Limp: The device business is less about building hardware for customers and more about building services behind that hardware. So the original vision of Kindle was to deliver any book ever written in less than 60 seconds, and that was all about creating a cloud-based service that had a great catalogue of books, great selection, and great prices. And as we've rolled out devices since then, everything from Fire TV to, as you mentioned, Echo and Alexa and everything in between, it's about creating that backend service that constantly improves and adds value for customers, and isn't just a gadget but instead a full end to end service that can benefit what customers want.